1. Field of the Invention
The present invention relates to a repaired structure of a circuit board having pre-soldering bumps and a method for repairing the same, and more particularly, to a method for repairing a defective pre-soldering bump by a micro-electrode.
2. Description of the Prior Art
With demand for increasing various portable electronic products, recent packaging techniques for integrated circuits is in line with the trend toward miniaturization and higher density. Thus, packaging techniques with highly integrated circuits such as a ball grid array (BGA) package, a flip chip package, a chip size package (CSP) and a multi-chip module (MCM) package have been developed as a consequence. Moreover, the so-called packaging density of the integrated circuits refers to the number of pins within a unit area. With regard to an integrated circuit package with a high density, as the length of wires becomes shorter, the speed of signal transmission can be improved. Therefore, the application of bumps has become a mainstream in the high-density packaging techniques.
In the exemplification of the flip chip package, electrode pads are formed on an active surface of a semiconductor chip and corresponding conductive pads are formed on a circuit board, such that the electrode pads formed on the active surface of the semiconductor chip can be electrically connected to the circuit board by the means of pre-soldering bumps or other conductive adhesive materials formed between the semiconductor chip and the circuit board, wherein the pre-soldering bumps or the conductive adhesive material allows the semiconductor chip to electrically and mechanically connect to the circuit board.
During the fabrication of pre-soldering bumps, however, defects of pre-soldering bumps may exist due to some unavoidable reasons such as operating conditions, equipment or other process factors. The common defects of pre-soldering bumps include bumps which have no, insufficient or excessive soldering materials. Besides, an oversized or undersized bump will cause inconsistent heights of the bumps, such that the attachment and electrical performance between the semiconductor chip and circuit board will be adversely affected in subsequent packaging processes. Furthermore, with the trend of the continuous miniaturization of semiconductor components and the continuous improvement of circuit integration, a tinny little defect during the packaging process will still seriously ruin the quality of electrical devices.
Referring to the prior art, if a defective bump is detected before a reflow-soldering process, the defective bump cannot be repaired. Instead, the defective bump has to be accepted or the whole circuit board needs to be reworked. If a defective bump is detected after the reflow-soldering process, the whole circuit board needs to be scrapped as there is no remedy. Thus, the prior art is not cost effective and results in a big waste of materials.
Accordingly, the problem to be solved herein is to provide a repaired structure of a circuit board having pre-soldering bumps and a method for repairing the same, by which a process yield can be improved and the production cost can be reduced.